The present invention relates to rheological additives in the form of a preactivated pastes, to a specific process for the preparation of these additives, to specific compositions comprising the said additives, and also to a specific process for the preparation of said compositions, to specific uses and to the specific coatings obtained from said additives. These specific additives allow the modification of the viscosity of sealant compositions, glue compositions, adhesive compositions, coating compositions, such as paints, varnishes, gel coats or inks, or molding compositions.
The state of the art reveals sealant compositions, adhesive compositions or coating compositions based on polyurethane comprising an additive of non-reactive polyamide type for adjusting the viscosity of said compositions. Specifically, EP 467 533 describes a polyamide obtained from at least one polycarboxylic acid chosen from sebacic acid, azelaic acid, dodecanedioic acid and fatty acid dimers or trimers with at least one component containing an —NH2 or —NH group chosen from primary or secondary monoamines natural or synthetic, saturated or unsaturated, either ethylenically or acetylenically unsaturated. The obtained polyamide rheological additive can be prepared as a powder, or in combination with a solvent or a plasticizer, forming a liquid or a paste, said polyamide being previously diluted therein.
JP 2004107543 discloses a thixotropic additive in the paste form which is free from granular particles, said paste being the product of the reaction between a diamide component and an epoxy resin added at the end of the synthesis step, said diamide component being chemically modified in order to be able to react with the epoxy resin.
Furthermore, JP 2002146336 discloses the preparation of a rheological additive in the paste form obtained from a blend of fatty acid diamides, dispersed in an alcohol-based solvent, of a compound of cycloaliphatic type and of an ester. The obtained dispersion is then subjected to a thermal treatment. The final paste does not comprise any plasticizer; it is subsequently used as thixotropic agent in unsaturated polyester resins.
JP 63-15876 discloses a mixture of hydrogenated castor oil fatty acid and of saturated C14-C18 fatty acid with ethylene diamine or 1,4-diaminobutane, the mixture forming a thixotropic agent which can be used in one-component polyurethane sealant compositions. However, said thixotropic agent is not provided in the form of a preactivated paste which can be used without any preliminary activation.
Other rheological additives can be used to increase the viscosity of solvent-based or solvent-free sealants or adhesive systems. Among them we may cite polyamide powders, powders based on hydrogenated castor oil derivatives, fumed silicas, precipitated or ground calcium carbonates. The fumed silicas and calcium carbonates are of mineral (inorganic) nature and require a very high speed dispersion of the mixture. However, these inorganic fillers exhibit problems of stability and of sedimentation over time, with resulting negative effects on the mechanical properties of the final system. Another particular disadvantage of polyamide powders and of powders formed of derivatives of hydrogenated castor oil, is the need for the end-user (formulator) to activate the system (powder) during the production of the final application composition. This activation requires high speed shearing, and heating to temperatures ranging up to near 120° C. depending on the products, and also a necessary minimum dwell time (duration), depending on (determined by) the temperature conditions and on the system (polarity), in order to develop optimum final rheological properties. These additives confer, on the composition into which they are incorporated, a thixotropic behavior characterized by a significant shear thinning, that is to say a reduction in the viscosity when the shearing increases and then a time-dependent recovery of the viscosity (equivalent to a hysteresis effect). Additives of this type provide the final composition with excellent applicative properties which are characterized by high viscosity at rest, good stability of this viscosity on storage, good resistance to sedimentation, ease of application and of extrusion and good sag resistance once applied. Despite the fact that additives of this type provide the final composition with good properties, they exhibit, as a main disadvantage, the fact that they do need an activation step, which is sometimes difficult to control or to reproduce by the end-user, and costly in terms of both time and of energy.
The technical problem of the invention, with respect to the cited prior state of the art, thus consists to develop an improved product (additive) exhibiting comparable properties to those shown by polyamide powders and hydrogenated castor oil derivatives, but without requiring a phase of activation by the end-user, said product consequently being much easier and much faster to use by the end-user, with further specific advantages linked to the resolution of this general problem. The term “in the preactivated paste form” should be considered as meaning that the additive is ready-for-use by the end-user (formulator of sealants, of glues, of adhesives or of coatings, such as paints or varnishes or gel coats or inks, or of molding compositions), by simple mixing into the final application formulation, without needing any specific in situ activation in the said formulation (requiring specific conditions of temperature, of shearing and of duration to be respected).
More particularly, the advantages linked to the resolution of the general technical problem with respect to the prior art are as follows:
low Volatile Organic Compounds (VOC) emissions and reduced risk of inflammation or of explosion,
absence of handling pulverulent (micronized) powders by the end-user, thus preventing dust formation in the atmosphere and on the production site of the final compositions and consequently the need for ventilation due to the risk of dust inhalation,
possibility of handling in the absence of any solvent in the final formulation, it being possible for the additive to be used both in solvent-based application compositions and in solvent-free compositions,
flexibility of use and of handling, the preactivated paste being easy to disperse in the composition, either at the same time as the fillers at the beginning of production, or at the end of processing, while conserving rheological properties at least equivalent to those obtained from powders of polyamide or diamide type or castor oils according to the prior art,
finally and in particular, no need for the activation stage, the processing of the additive according to the invention requiring neither heating nor high shearing nor an activation time, which allows a saving:                in terms of production time, since there is no heating stage and since the cooling stage is shortened, even avoided, during the preparation of the final composition,        in energy, due to the absence of the heating and cooling stages,        in productivity for the end-user,        in reproducibility and reliability of the final end-use performances.        
Thus, the first subject matter of the invention is a rheological additive in the form of the preactivated paste, comprising:                A) at least one fatty acid diamide introduced in the powder form, it being possible for said powder optionally to comprise, in addition to said diamide, hydrogenated castor oil,        B) at least one organic plasticizer, said plasticizer being liquid at room temperature.        
The second subject matter of the invention is a process for the preparation of such rheological additives by dispersion and activation under controlled heating.
The invention also relates to a composition of organic binder or of pigment concentrate or of fillers comprising a rheological additive according to the present invention and to the process for the preparation of such a composition.
Another subject matter of the invention is the use of the rheological additive or of the composition according to the invention in coating applications for paints, varnishes, inks, gel coats or plastisols based on PVC or for applications of sealants, glues, adhesives, sealers or of molding compositions or also for cosmetic applications.
Finally, a last subject matter of the invention relates to finished articles, such as coatings, seals, molded composites or components, or cosmetics, obtained from the additive or from the composition according to the invention.
The first subject matter of the invention is thus a rheological additive in the form of a preactivated paste, comprising:                A) at least one fatty acid diamide introduced in the powder form, it being possible for said powder optionally to comprise, in addition to said diamide, hydrogenated castor oil,        B) at least one organic plasticizer, said plasticizer being liquid at room temperature.        
Said rheological additive in the form of a preactivated paste preferably exhibits a dynamic elastic modulus G′, measured on said mixture A)+B), at a temperature of 23° C. and under a frequency of 1 Hz, higher than or equal to 104 Pa, preferably higher than or equal to 8×104 Pa and more preferably still higher than or equal to 5×105 Pa. This characteristic does significantly show the effective activation of the preactivated additive.
Preferably, said plasticizer is a polar organic plasticizer bearing at least one polar group, preferably an ether group and/or an ester group and/or an epoxy group.
Said plasticizer can first bear at least one ether group, and in this case it can be chosen from polyethers, such as homopolymers and/or copolymers of ethylene oxide and/or of propylene oxide and/or a blend of said polyethers (homopolymers and/or copolymers) and/or their derivatives, these derivatives comprising, inter alia, said polyethers which are blocked at the chain end by a C1 (methoxy) to C4 (butoxy) alkoxy group or by a C2 (acetate) to C4 (butyrate) ester group, said polyethers having a weight-average molecular weight Mw ranging from 150 to 6000 and preferably from 1000 to 3000. The term “copolymer” is to be interpreted as comprising both random and block copolymers.
Said plasticizer may further bear at least one ester group and it may be chosen from monoesters and/or polyesters (multi- or poly-functional esters) obtained from C4 to C21 alcohols, which alcohols are optionally alkoxylated, for example with 1 to 10 alkoxy units chosen from oxyethylene (OE) and/or oxypropylene (OP) units, and from mono- or polyacids with a functionality ranging from 1 to 4 selected from:                organic acids chosen from aromatic acids having a chain length (without —CO2H functional group) ranging from C6 to C10 and/or aliphatic acids having a chain length (without considering the —CO2H functional group) ranging from C4 to C18, or        inorganic acids.        
The esters of aromatic acids may be chosen from phthalic esters (phthalates) and trimellitic or trimellitate esters (benzene 1,2,4-tricarboxylate) and their trimesitate or trimesate isomers (benzene 1,3,5-tricarboxylate). The esters of aliphatic acids can be chosen from adipic esters (adipates), citric esters (citrates), sebacic esters (sebacates) and azelaic esters (azelates). The esters of inorganic acids can be chosen from sulfonic esters (sulfonates), in particular C10 to C21 alkyl sulfonates, sulfuric esters (sulfates), sulfinic esters (sulfinates), phosphoric esters (phosphates), phosphonic esters (phosphonates) and phosphinic esters (phosphinates).
Finally, said plasticizer may also bear at least one epoxy group and may be chosen from epoxidized oils based on fatty acid, the chain length of which can range from C16 to C18, such as epoxidized soybean oil.
Preferably, in said rheological additive, there is an absence of any other compound selected from alcohols with a molecular weight Mw<150, such as methanol, ethanol, propanol, butanol or benzyl alcohol, or selected from polar aprotic solvents, such as N-methylpyrrolidone, N-ethylpyrrolidone, N-butylpyrrolidone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N,N,N′,N′-tetramethylurea, hexamethylphosphoramide, hexamethylphosphorous triamide or propylene carbonate.
Among the preferred plasticizers can be cited those comprising at least one C6 to C10 aromatic acid ester group, in particular plasticizers selected from mono- and/or dialkyl phthalates and more preferably still from dialkyl phthalates, with it being possible for said alkyls to be identical or different and chosen from C7 to C18 and preferably C10 to C12 alkyls.
The most preferred in this family of plasticizers (dialkyl phthalates) is di-iso-undecyl phthalate. The most preferred in the family of polyethers are the polyethers which are homopolymers of propylene oxide (polypropylene glycols) with a weight-average molecular weight Mw ranging from 1000 to 3000, more particularly polypropylene glycol (PPG) with an Mw equal to 2000, and/or their derivatives chosen from monoesters, preferably C2 to C4 monoesters, or C1 to C4 monoethers, such as monomethoxy or monoethoxy derivatives.
Said plasticizer can have a boiling point higher than 200° C. and preferably higher than 250° C. (at atmospheric pressure). It must be liquid at room temperature in order for said diamide to be dispersible in said plasticizer.
The rheological additive according to the invention preferably exhibits a maximum penetration value or consistency, measured according to standard ASTM D 217, of less than 15 mm, more preferably of less than 10 mm and more preferably still of less than 5 mm.
Said fatty acid diamide introduced in the powder form has a particle size of less than 100 μm and preferably of less than 50 μm and more preferably at least 90% of said diamide has a particle size of less than 20 μm and preferably of less than 15 μm.
The weight ratio of the fatty acid diamide can vary from 10 to 40% and preferably from 15 to 30%, with respect to the mixture A)+B).
A fatty acid diamide suitable for the invention, can be obtained by polycondensation between at least one C2 to C12 primary diamine and at least one monocarboxylic acid with a chain length of C3 to C22, it being possible for the reaction product optionally to be diluted in hydrogenated castor oil and in this case to a weight ratio varying from 10 to 100% by weight, with respect to the diamide+hydrogenated castor oil total, preferably to a weight ratio varying from 20 to 100% by weight. The hydrogenated castor oil can be used to adjust the affinity of the final mixture (diamide+hydrogenated castor oil) with respect to the composition of the final application formulation.
In the case where the diamide is diluted in hydrogenated castor oil, the addition takes place at a temperature of between 140 and 220° C. At the end of the addition, a solid mass is obtained and is milled (micronized).
According to a preferred embodiment of the invention, the rheological additive according to the invention is obtainable by a specific process, such as described below.
The specific process for the preparation of said rheological additive, which is the second subject matter of the invention, comprises the following steps                i) progressive dispersing of said diamide in the powder form in the plasticizer until a homogeneous dispersion is obtained, at room temperature controlled by virtue of regulation of the temperature, the diamide and said plasticizer being as defined above,        ii) maintaining the homogeneous dispersion obtained during stage i) at least one isotherm with a corresponding temperature ranging from 50 to 120° C. and preferably from 60 to 100° C., for a period of time of 1 to 100 hours, preferably of 6 to 80 hours and more preferably still of 15 to 40 hours.        
The choice of the temperature and the duration of step ii) depends on the polarity of the plasticizer and on its chemical affinity with said fatty acid diamide.
The homogeneity of the dispersion is characterized by an absence of granular particles (bits) when the film of said dispersion is applied between two glass sheets (glass sheets test). In order to obtain this homogeneity, said diamide is dispersed in said plasticizer at a shear rate preferably of between 2 and 6 m·s−1 for a preparation on the laboratory scale with a volume not exceeding 1 liter.
The end of step ii), also known as “activation or maturation step”, is characterized by a maximum penetration value or consistency of the formed paste of less than 15 mm, preferably of less than 10 mm and more preferably still of less than 5 mm, measured according to standard ASTM D 217. This maximum penetration value is to be associated with a reference method for the preparation of said preactivated paste, which corresponds to a preparation on the laboratory scale with a volume not exceeding 1 liter, the sample being thus perfectly homogeneous. The method for the preparation of said preactivated paste is described below in the examples according to the invention.
The third subject matter of the invention relates to a composition formed of organic binder or of pigment concentrate or of fillers comprising at least one rheological additive as defined according to the invention or obtained according to the process as defined according to the invention, it being possible for said binder composition to be a coating composition for the protection and/or decoration and/or surface treatment of various substrates, said coating composition may be selected from paints, varnishes, pigmented or clear gel coats, inks or plastisols based on PVC, or it being also possible for the said binder composition to be a sealant, glue, adhesive or sealers composition, or also a molding composition for molded composites or for molded pieces (parts or articles), SMC or BMC or laminates type, boat hull or composite panel types, or pieces molded by casting, with application of the composition with a brush or with a roller, or by spraying with a spray gun, or finally a cosmetic composition.
Said rheological additive according to the invention as described above can be present in said composition at a weight ratio varying from 1 to 40%, preferably from 15 to 30% and more preferably still from 10 to 20%, with respect to the total weight of said composition, and said diamide can be present as dry active material, at a weight ratio varying from 0.1 to 16%, preferably from 0.2 to 8% and more preferably still from 1 to 6%, with respect to the total weight of said composition.
The composition according to the invention can comprise other components, such as, for example, fillers, plasticizers, wetting agents or also pigments.
According to a more particular embodiment, the organic binder composition according to the invention is crosslinkable, either thermally or by irradiation under radiation, such as UV radiation (in the presence of at least one photoinitiator) and/or EB radiation (electron beam, without initiator), including self-crosslinkable at room temperature, or it may be non crosslinkable. The organic binder composition can be a one-component crosslinkable composition (just one reactive component) or a two-component crosslinkable composition (binder based on two components which react with one another by mixing during use).
Said organic binder can be selected from at least one epoxy/amine (crosslinkable two-component) reactive system, an unsaturated polyester, a vinyl ester, an epoxidized resin, a reactive silicone resin, an alkyd grafted by a polyester or a polyamide or an alkyd modified by diurea/diurethane or an ungrafted alkyd, a polyurethane or a silicone, a crosslinkable two-component polyurethane, a polysiloxane, a polysulfide polymer, a reactive acrylic polymer, a (meth)acrylate multifunctional oligomer or acrylated acrylic oligomer or allylic multifunctional oligomer, a butyl rubber, polychloroprene or SBR type elastomer, or a silylated prepolymer or polymer, preferably a silylated polyether or a silylated polyurethane, or a silylated polyether-urethane with an —OH or —CO2H functional group.
In a more specific case, said organic binder can be selected from the following crosslinkable two-component reactive systems epoxy/amine or epoxy/polyamide systems comprising at least one epoxy resin comprising at least two epoxy groups and at least one amino or polyamide compound comprising at least two amine groups, polyurethane systems comprising at least one polyisocyanate and at least one polyol, polyol/melamine systems, and polyester systems based on at least one epoxy or on one polyol which reacts with at least one acid or corresponding anhydride.
According to other specific cases, said organic binder can be a crosslinkable two-component polyurethane system or a crosslinkable two-component polyester system from an epoxy/carboxylic acid or anhydride reaction system, or from a polyol/carboxylic acid or anhydride system, or from a polyol/melamine reaction system in which the polyol is a hydroxylated acrylic resin, or a polyester or a polyether polyol.
According to an alternative form, the organic binder composition according to the invention is a sealant, glue, adhesive or sealer composition which is self-crosslinkable and based on polyether-silane or on polyurethane-silane.
More particularly, the organic binder composition according to the invention can be a one-component sealant composition based on a silylated prepolymer or polymer, and preferably a silylated polyether or a silylated polyurethane (silylated polyether-urethane), such as Kaneka MS Polymer™ and Kaneka Silyl™. MS Polymers™ can be used in:                the construction and building industry for expansion joints, the fitting of glazing, carpentry joints, masonry joints, prefabricated materials (sandwich panels for refrigerated lorries, for example) or parquet flooring,        the naval industry, the motor vehicle industry (industrial bodywork, windscreen profile rubbers),        mass market (do it yourself: DIY market) for sealants and adhesives, with and without solvent,        civil engineering.        
Other components can be added to or substituted in one-component sealant compositions based on silylated prepolymer or polymer, such as other types of binders, colored pigments, various plasticizers, fillers of precipitated or ground calcium carbonate type, glyceride derivatives, silicas, such as fumed silicas, other additives, such as UV-A absorbers (UV antioxidants), such as 2,4-di(tert-butyl)-6-(5-chlorobenzotriazol-2-yl)phenol (Tinuvin® 327 from Ciba), light stabilizers based on sterically hindered amines, such as HALS (hindered amine light stabilizers), for example bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin® 770 from Ciba), waxes and other types of catalysts, such as tin salts.
The invention also comprises a process for the preparation of said composition according to the invention, said process comprising the following stages                i) addition of said additive according to the invention to said composition,        ii) homogenization of the mixture with a agitator and/or planetary mixer and/or high speed disperser, without having any need, at this stage, to apply any activation treatment.        
Said process for the preparation of said organic binder composition according to the invention can also comprise a preliminary stage of preparation of said additive according to the following steps                i) preparation of an additive according to the invention according to the process for the preparation of said additive of the invention as defined above,        ii) addition of said additive obtained according to step i) to said composition as defined above,        iii) homogenization of the mixture in an agitator and/or planetary mixer and/or high speed disperser, without having any need, at this stage, to apply any activation treatment.The term “high speed” means tangential speeds ranging from 2 to 15 m·s−1.        
Another subject matter according to the invention relates to the use of at least one rheological additive or of a composition according to the present invention, without the need for in situ activation, by simple addition to and homogenization in the final formulation. More particularly, said rheological additive and said composition can be used in coating applications, such as coatings for paints, varnishes, inks, pigment-comprising or pigment-free gel coats or plastisols based on PVC, or in sealants, glues, adhesives or sealers applications, molding composition applications for composites, molded compounds or SMC/BMC laminates, or in cosmetic applications, such as nail varnishes.
Finally, the last subject matter of the invention relates to the finished items, such as coatings, obtained from the use of at least one rheological additive or from the use of a composition according to the present invention or by the use of the respective preparation processes, said coatings being selected from paints, or varnishes, or inks, or pigmented or clear (non-pigmented) gel coats, or plastisols based on PVC, or sealants, or glues, or adhesives, or sealers (seals), or composites, or molded components, or SMC/BMC laminates resulting from molding compositions, or also cosmetic products, such as nail varnishes.
By way of illustration of the invention, the following examples demonstrate, without any limitation, the performance of the rheological additive according to the present invention.